Sieve for paper-making machines



Nov. 11, 1969 B. 00mm 3,477,477

SIEVE FOR PAPER-MAKING MACHINES Fil ed May 20. 1966 2 Sheets-Sheet 1United States Patent 3,477,477 SIEVE FOR PAPER-MAKING MACHINES BernhardDomin, Bonn, Germany, assignor to Dr. Plate GmbH Chemisehe Fabrik, Bonn,Germany, a corporation of Germany Filed May 20, 1966, Ser. No. 551,693Claims priority, applicatiol (ermany, May 25, 1965,

8 Int. Cl. D03d 27/00, 13/00, 1/00 US. Cl. 139-383 3 Claims ABSTRACT OFTHE DISCLOSURE This invention relates to woven structures such asscreens or sieves made from synthetic filaments, and particularly toso-called wires for paper-making machines, which consist of a web ofwoven material joined together at its ends to form an endless belt orscreen.

It is known in connection with paper-making machines that wires madefrom plastic are more resistant to abrasion than metal wires. The endsof a screen woven in web-fashion cannot be joined together to form anendless screen by welding together the adjacent synthetic filaments,because the strength of the joint obtained would be inadequate. Bondedlap points are not recommended because they impair the permeability ofthe screen. To obviate these disadvantages, circular looms of greatdimensions have been used to produce endless screens, thus avoiding theneed for joints. Unfortunately, excessive expense is involved with suchlooms.

Therefore, it is an object of the present invention to provide endlessscreens or sieves or the like woven from synthetic filaments with jointsof high strength in the woven structure which have little or no effecton the permeability of the screen.

Further objects of the present invention and advantages thereof willbecome apparent as the following description proceeds.

The present invention provides a screen or sieve woven from syntheticfilaments and, more particularly, a Wire for paper-making machines,which comprises an endless web of woven material the connections betweenthe ends of the individual warp filaments being distributed over a largearea of the web and the warp filaments being connected together at theirend faces pointing in the filament direction independently of the weftfilaments.

According to the present invention, therefore, the connections betweenthe individual warp filaments are distributed over a relatively largearea of the web in such a way that several connections do not lieimmediately adjacent each other in one row, so that instead of the usuallinear joint, the warp filaments at the ends of the screen are connectedtogether in a staggered relationship. If however there are twoconnections directly adjacent one another, there is still room formovement or yield towards the sides, because other connections arelocated further away.

Those ends of the warp filaments to be united are preferably cut at anangle with regard to the longitudinal direction of said filament and arebonded together. Since the individual connections do not lie in a row,but are distributed over a relatively large area, even a slightlythicker bond would not have any appreciable effect on the permeabilityof the screen. In a particular embodiment of the present invention, thewarp connections are alternately arranged in pairs, and not in randomorder, in one row at either end of the joint. Although imprints could inthis case be left behind by the two rows formed by the connections, theywould only appear as a dotted line at the ends of the joint.

In the attached drawing:

FIG. 1 shows in perspective an endless sieve in a paper-making machine;and

FIGS. 2 to 5 are plan views, on enlarged scales of sections fromdiiferent paper machine wires or screens, embodying variouspossibilities of connecting the warps together to form an endless"screen or sieve.

In FIG. 1 is shown an endless sieve 8 of which a part 9 is somewhatenlarged.

Each screen is woven in known manner from warp filaments A and weftfilaments B made from a synthetic material. For the sake of clarity, theconnections C have been shaded in the drawings.

Two rows and five rows, respectively, of warp connections C are shown atthe upper and lower ends, respectively, of FIGURE 2. The warp filamentsare connected together by cutting them at an angle and bonding themtogether. Between rows 1 and 2 there is a gap or interval of twouninterrupted mesh divisions, while the gap between rows 3 to 7 variesin size. Rows 1 and 2 are separated from rows 3 to 7 by eleven meshdivisions. The number of connections is irregularly distributed in allthe rows.

FIG. 3 shows another example, incorporating four rows 1 to 4 ofconnections C between warp filaments cut at an angle. In this case, too,the rows in each group 1-2 and 34 are separated from one another by twomesh divisions, while group 12 is separated from group 3-4 by thirteenmesh divisions.

FIG. 4 shows a six-row arrangement of connections in which the two outerrows 1 and 6 have as many connections C as the four inner rows 2 to 5together.

In FIG. 5, there are only two rows of connections between Warp filamentscut at an angle. These two rows are separated from one another bynineteen mesh divisions. In this case, the connections are alternatelyformed in pairs, and not in random order, in one row 1 or 2 at eitherend of the joint.

Each of the examples illustrated embodies the principle of theinvention, namely to form the connections between the warp filaments notin a line, as is the case with welded metal wires, but over an area withat least one uninterrupted mesh division and covering several wefts.This avoids an accumulation of bonds while the permeability of thescreen as a whole remains practically uniform. By virtue of the longoverlap between the warp filaments in the wide joint, the points atwhich they are bonded together remain largely unaffected by tensileforces because the entire woven or plaited structure carries the meshfield. This is another important advantage of the large-area screenjoint.

By virtue of the fact that, in the joining of the screen, the weftfilaments in this zone are not replaced or temporarily removed, the warpfilaments always fit exactly back into the kinks in the weft filaments,so that neither the mesh pattern nor the surface of the screen arealtered at the screen joint.

To increase its strength, the entire screen is advantageously coatedwith a plastic solution, preferably a polyurethane composition, afterthe warps have been bonded together. The coating can be hardened atnormal temperature or at elevated temperature. As a result, the warp andweft filaments are bonded together at their intersections, so that thestrength of the screen joint is increased and the mesh pattern is keptintact.

What we claim is:

1. An endless sieve for paper-making machines, said sieve comprisingwoven synthetic warp and weft filaments, in which, independently of theweft filaments, the warp filaments are connected together at endabutting faces pointing in the longitudinal direction of said warpfilaments, said warp filaments and said weft filaments remaining intheir original woven positions, the connections between said warpfilaments being arranged in at least two separate groups each includingat least one row such that the connections of the warp filaments are notall in the same row, said groups being separated from one another by atleast two mesh divisions, the connections between adjacent rows in eachgroup being spaced by at least one intact mesh division, said abuttingends being inclined at an angle with regard to the longitudinaldirection of the filaments and being disposed intermediate adjacent weftfilaments.

2. An endless sieve as claimed in claim 1, said sieve being providedwith a hardened plastic coating.

4 3. An endless sieve as claimed in claim 2, wherein the plastic coatingcomprises a polyurethane.

References Cited UNITED STATES PATENTS 926,004 6/ 1909 Keller 1393832,748,445 6/1956 Skeer 139383 3,060,547 10/1962 MacBean 139383 X FOREIGNPATENTS 767,619 10/ 1952 Germany.

11,073 6/1956 Germany. 1,186,730 2/ 1965 Germany.

2,966 11/1865 Great Britain.

949,779 2/1964 Great Britain.

HARRY B. THORNTON, Primary Examiner ROBERT HALPER, Assistant ExaminerUS. Cl. X.R.

